Rolled my kubota 7800... Now it wont turn over. Please HELP

[dodge man]

It happened to another member on TBN where a rod was bent. Think if just one cylinder had oil in it and it was near the bottom of its stroke, then the engine has some momentum from the starter by the time the cylinder gets to TDC. I hope thats not what happened.

 

[tombodett]

Ok so other then taking it to the shop for a compression check, what is the easiest way to find out if there is a bent rod? I appreciate all the input and if no other positives came out of this experience. I have learned a lot about my tractor and look forward to learning more.

 

[dodge man]

Here is a link to the thread I was talking about. Hope this didn't happen to yours. Towards the bottom of the page is some pics.

http://www.tractorbynet.com/forums/yanmar-new/216600-rolled-my-yanmar-ex3200-have-4.html

 

[hutchman]

Ok so other then taking it to the shop for a compression check, what is the easiest way to find out if there is a bent rod? I appreciate all the input and if no other positives came out of this experience. I have learned a lot about my tractor and look forward to learning more.

The case I described was an older engine and it was the push rod that actuated the valves via the lifter that was bent. In your case it's probably a piston rod like the picture in the link doge man mentioned. Depending on what cylinder it is, you could drop the oil pan and look up and see the crankshaft and piston rods. If you have glow plugs, you can remove them to relieve the compression and have someone turn the engine over by hand (usually by a bolt on the crank) and watch the pistons go up/down and hopefully see enough of the rod to determine if it is OK. If you did this then you're talking about an oil change and maybe a gasket for the oil pan.

You can buy diesel compression test kits at places like Harbor Freight, I think Northern has one etc., just depends on how deep you want to get. Would be nice if you could determine the problem then you could direct the shop to the problem.

 

[tombodett]

Well ****, there goes another $40 cause I just changed the oil. A buddy of mine said maybe the fuel filter got plugged by debris from being on its side so I think I'll start there then pull the pan and see if I can spot a bent rod.

 

[hutchman]

Well ****, there goes another $40 cause I just changed the oil. A buddy of mine said maybe the fuel filter got plugged by debris from being on its side so I think I'll start there then pull the pan and see if I can spot a bent rod.

... well, I guess if your're clean you could drain and reuse it ... but at this point $40 is probably the least of your worries I'm sorry to say.

 

[JRobyn]

IF (big if) you can actually see any part of the top of the pistons through either the injector holes or glow plug holes, you can simply turn the engine over slowly by hand while watching each piston at the top of its stroke. If a connecting rod is bent, the piston in that cylinder will not rise as high at the top of the stroke. Shouldn't cost anything but the time to check this way.

Even if you can't actually see the piston tops, you can sometimes use a piece of soft material (wooden dowel, soft solid copper wire) down into the cylinder to "measure" the top of stroke, but this will require being very careful to have your measurer placed exactly the same in each cylinder and then some marking/measuring to see if they are exactly the same.

- Jay

 

[hutchman]

IF (big if) you can actually see any part of the top of the pistons through either the injector holes or glow plug holes, you can simply turn the engine over slowly by hand while watching each piston at the top of its stroke. If a connecting rod is bent, the piston in that cylinder will not rise as high at the top of the stroke. Shouldn't cost anything but the time to check this way.

Even if you can't actually see the piston tops, you can sometimes use a piece of soft material (wooden dowel, soft solid copper wire) down into the cylinder to "measure" the top of stroke, but this will require being very careful to have your measurer placed exactly the same in each cylinder and then some marking/measuring to see if they are exactly the same.

- Jay

That's a good idea ... or get you one of these:
Digital Inspection Camera

*Edit: You need to use this opportunity with you're wife to justify some cool new tools!

 

[Ironmagz]

Well it's been over two weeks now. Is there any new news on this? I would really like to know what was found!

 

[JWR]

A couple of thoughts-- Unless a cylinder fired when you first turned it over the rod is probably not bent. I don't think a starter ever bends a connecting rod. If the rod were bent (and you say it runs but at about 75% power level) it would make a heck of a noise. If it seems to run OK but at a poor power output level I think you just disabled one of the cylinders somehow. Since you had the injectors loose, probably one of them is fouled up/needs bleeding.

Do let us know the outcome.